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Re: sauropod faces and ankylo tracks

Sebastian Apesteguia (sebapesteguia@yahoo.com.ar) wrote:

<The problem is in the sauropod nostrils. After Witmer, it is obvious a nostril
as fore as we can within the narial cavity, but...what about the telescoped
nostrils of several sauropods? We have three different opinions in the three
main paleoartists involved:>


  I favor the midway approach with a twist:

  The muscle is highly vascularized around the teeth and so it is unlikely the
softer soft tissue was as extensive, such as that the flesh was so close to the
surface of the bone that the bone growth developed around the blood vessels and
nerve tracts that mark the surface of the premaxilla, maxilla and dentary in
"horse-snouted" sauropods such as diplododines. The paired smooth surfaces
across the dorsal surface marks only the extent of soft-tissues probably not
appressed to the skull, but it is entirely possible cartilagenous structures
expanded this region as around the orbital region of modern reptiles such as
varanids. This this is possible for dinosaur snouts, then diplodocids may also
sport such structures above the skull accompanying the nasal passage rostrally.
If so, it seems possible to me that these tissues can form a variety of shapes
above the skull, including making loops, increasing the passage, orienting
nostrils caudally or laterally above the anterior region of the fossae, and so
forth. But likely they were around the anterior region of the fossae, as
described by Witmer. Thus, I would favor the midway hypothesis as the best data
to fit the facts without describing unknown extra features. I have of late
drawn cartilage structures similar to brachiosaur nasal arches above the
diplodocid snout, but not quite so large or prominent. The bony external naris
and the nostril are not confluent, and this gives a lot of room to fudge.


Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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